KR100684185B1 - Thixotropical grout - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasticized grout injection material used for filling back voids or cavities, and to filling voids or cavities generated on the back of the structure and the ground. Not only can it be controlled, but also has a fast roughing properties and durable plasticizer grout, to provide a plasticizer grout in combination with silica colloid, cement, superabsorbent polymer and calcium sulfoaluminate (CSA) fastener.

Back Injection, Joint Filling, Plastic Grout

Description

Plastic phase grout injection material {THIXOTROPICAL GROUT}

Fig. 1 is a model of the Japanese AND company SV-10, which is a digital vibration type viscometer used to observe the change in viscosity of a plastic grout material.

Figure 2 is a graph showing the viscosity change with time of the plastic phase grout material of Example 1,

Figure 3 is a graph showing the viscosity change with time of the plastic phase grout material of Example 2,

Figure 4 is a graph showing the viscosity change with time of the plastic phase grout material of Comparative Example 1,

5 is a graph showing the viscosity change with time of the silicic acid-based plastic phase grout material,

Figure 6 is a photograph showing the results of immersing the grout gel of Example 1 and Comparative Example 1 for 180 days.

 BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic phase grout injector, which is used to fill back voids or cavities, comprising silica colloids, cements, superabsorbent polymers, and calcium sulfoaluminate (CSA) fasteners.

In the process of civil engineering, such as tunnel excavation or underground excavation, a cavity may occur at the interface between the civil structure and the ground, or a large gap or overhole may occur in the ground. In this case, there is a high possibility of groundwater leakage, loss of soil, and collapse by ground deformation. In particular, in the case of shield tunnels, which are recently increasing, it is necessary to fill them due to voids between segments and the back ground during drilling.

In order to prevent the above problems, a method of filling by filling a simple one-liquid cement milk or silicic acid-based grout into the pores or cavities on the back. However, as described above, the simple one-component cement milk ground injection material does not maintain viscosity and strength more than a certain level before being completely cured after injection, as well as is easily diluted and lost by groundwater.

In recent years, plastic phase grout has been used as a ground injection material to improve the injection effect and quality. Unlike ordinary cement-based injection materials, such plastic phase grout has fluidity due to low viscosity when injected into a cavity, but since the viscosity gradually rises to a certain level after a certain time, the viscosity increases for a predetermined time. Has thixotropic properties (plasticity). Therefore, not only the fine space can be filled by pressurization, but also after a certain period of time, the viscosity is increased, so that a certain level or more of strength is developed. As such plasticizing grout materials, a method of combining bentonite and sodium silicate in cement milk is known. This is a kind of ground injection material used in the conventional ground injection method such as L.W. However, in the case of an injection material combining bentonite and sodium silicate in cement milk, there is a problem that durability decreases with time due to alkali elution resulting from the use of sodium silicate.

As another plastic phase grout material, it is known to combine cement milk with aluminum salt-based or clay mineral-based fasteners, and Korean Patent Laid-Open No. 2001-0090686 discloses a plastic phase grout combining cement milk and a basic alumina sulfate solution. . However, combining basic alumina sulfate solution with cement milk does not reach the level required in the art as a whole in terms of plastic phase retention time, viscosity characteristics, and early strength development, and thus there is a problem that its use is limited.

In addition, the Republic of Korea Patent No. 10-0402456 has a neutral silica sol (silica) as a ground solid material exhibiting a plastic phase property having good permeability to the ground for the purpose of reinforcing and order of the ground, not for the purpose of joint filling or back injection. Colloids) are described. However, since the neutral silica sol is combined with particulate cement and particulate slag having a specific surface area of more than 4,000 cm ² / g and uses sodium bicarbonate as a viscosity time modifier, it is excellent in final strength and durability but has a long viscosity increase time and early strength. low. Therefore, although it is suitable as a ground fastening material that penetrates into the ground and is integrated with soil, there is a problem that it is not suitable for direct application as a lining back injection material or a joint filler of a shield tunnel.

In order to solve the above problems, the present invention can smoothly control the time to maintain plasticity, and is excellent in roughness, and excellent in properties such as durability and long-term stability. It is an object to provide a plastic phase grout injection material.

The plasticized grout injection material according to the present invention is a combination of 100 to 200 kg of silica colloid, 200 to 400 kg of cement, 0.5 to 2.0 kg of superabsorbent polymer resin, and 5 to 20 kg of calcium sulfoaluminate type fastener per 1 m ^{3 of} grout injection material. It characterized in that it comprises water.

In the injection material of the present invention, the silica colloid not only induces the initial gelation of the grout injection material of the present invention but also expresses the long-term strength and durability of the gel in its final state. The silica colloid may be used without limitation in the kind thereof, as long as those known in the art to be used in the manufacture of plastic phase grout material, prepared by the method of the Republic of Korea Patent Publication No. 10-2004-0100603 invented by the inventors As the silica colloid, a superabsorbent poly (acrylate-acrylamide) crosslinked copolymer is contacted with an aqueous solution of silica sol, and then the superabsorbent resin absorbing water from the aqueous solution of silica sol is separated from the solution of silica sol, and then It is preferable to use the silica colloid manufactured by the concentration method which removes water from a silica-sol urea by repeating operation | movement which discharges water by exposing to water and raising a temperature once or more.

It is preferable that the average particle diameter of the said silica colloidal particle used for this invention is 10 nm or more, and it is more preferable that it is 30-40 nm. If the average particle diameter of the silica colloidal particles is less than 10 nm, it is not preferable because the binding strength with the cement is weakened and the final strength is lowered. The content of the silica colloid is preferably 100 ~ 200kg per 1m ³ of the plastic phase grout injection material. If the content of silica colloid is less than 100kg, the overall solid content is lowered, which is not preferable because the final strength is lowered, and if it exceeds 200kg, the viscosity increases during the operation, which is not preferable because it causes difficulties in operation and is not economical. .

In the injection material of the present invention, the cement is a component that becomes a basic matrix of the grout injection material of the present invention. In the present invention, as the cement, those known to be used in the manufacture of plastic phase grout materials in the art can be used without limitation in its kind, and general portland cement, slag cement and micro cement can be used, in particular, Portland. Preference is given to using cement. The content of the cement is preferably 200 ~ 400kg per 1m ³ of the plastic phase grout injection material. If the content of cement is less than 200kg is not preferable because the final strength is lowered, and exceeding 400kg not only shorten the plastic phase holding time but also is not economical is not preferable.

In the injection material of the present invention, the superabsorbent polymer resin is not dissolved in water, and because the material itself sucks water, the absorption amount is much higher than that of cotton wool or cotton cloth, so that water absorbs tens to hundreds of times its own weight. It has the ability to hold. In addition, it has the property of not releasing water even if the pressure is applied as much as ween. This resin is a polymer in which a bridge or an insoluble portion is introduced into a polymer electrolyte, and is made by graft hybrid polymerization of acrylonitrile to starch (potato starch) or cellulose, and a mixture of acrylic acid and vinyl alcohol. Block interpolymers and the like can be used in powder or fiber form. The superabsorbent polymer resin used in the present invention has the ability to absorb and repair more water than its own weight under ordinary conditions such as pure water, but when it is added to a cement milk suspension, Absorption capacity is remarkably reduced by the cement ion component melt | dissolved in large quantities. Accordingly, even when the superabsorbent polymer resin used in the present invention is added to the cement milk liquid, only a slight increase in viscosity appears, and there is no problem in compounding use. However, when the cement milk containing the superabsorbent polymer resin powder is added to the silica colloidal solution used in the present invention, the ion concentration in the mixed solution is lowered while the cement ion component is fixed by the reaction between the cement component and the silica colloidal solution. do. As a result, the superabsorbent polymer resin recovers its absorbency and begins to absorb a large amount of water. This gradually raises the viscosity of the mixed liquid. Therefore, when the superabsorbent polymer resin is not added to the plastic phase grout injection material of the present invention, only a viscosity increase in the process of curing by the reaction between cement and silica colloid appears, so that the viscosity increase time is relatively delayed. As a result, the viscosity rise time of the blend is significantly different depending on the presence or absence of the superabsorbent polymer resin. In addition, the absorbent ability of the superabsorbent polymer resin serves to lower the content of water in the blend, thus contributing to the expression of coarse solidity after the grout gels.

The superabsorbent polymer resin used in the present invention preferably has a water absorption capacity of 250 times or more of its own weight, and more preferably an acrylic superabsorbent resin such as a poly (acrylate-amide) crosslinked copolymer. If the absorbency of the superabsorbent polymer is less than 250 times its own weight, the object of the present invention cannot be obtained, which is not preferable. The content of the super absorbent polymer resin is preferably 0.5 to 2.0 kg per 1 m ³ of the plastic phase grout injection material. If the content of the superabsorbent polymer resin is less than 0.5kg, the effect of addition is not so small that the object of the present invention can not be obtained. It is not preferable because the phenomenon of expansion and destruction in water appears.

 When the injection material is blended with water, the viscosity increases after blending and starts to appear in a plastic state within 5 minutes, and maintains the plastic state for 10 to 60 minutes, after which a non-flowable gel is formed.

In the plastic phase grout injection material of the present invention, calcium sulfoaluminate type fastener (CSA) may be added to improve the plasticity and roughness of the injection material. When CSA is mixed with cement, it is hardened by hydration, and crystals such as ettringite (3Cao · Al ₂ O ₃ · Sio ₂ ) or calcium hydroxide are formed and developed in the fine pores of the cement hardener. Ettlingite produced by the hydration reaction is a very small crystal of several micros, which is colloidally foamed into microscopic pores between gels during the hardening of cement paste, reducing shrinkage and dry shrinkage due to curing, and filling the pores. Thereby densifying tissue to enhance strength. The content of the calcium sulfonate-based fastener used in the grout injection material of the present invention is preferably 5 ~ 20kg per 1m ³ of the plastic phase grout injection material. When the content of the calcium sulfonate-based fastener exceeds the above range, it is not preferable because not only the plasticity time is shortened but also the coarsening effect is not large.

Since the grout injection material of this invention can adjust the viscosity retention time range, it can be constructed by one-component and two-component systems as follows.

(1) one-component system

In a combination container such as a mixer, silica colloid, cement, superabsorbent polymer resin, and calcium sulfoaluminate type fastener are added to water or aggregate and additives if necessary, and combined at once, and pumped into one infusion pump. It is performed by injection into a desired cavity or the like.

(2) two-component method

A mixture of silica colloids and, if necessary, aggregates and additives is called solution A, and a combination of cement, superabsorbent polymer resin, and calcium sulfoaluminate-based fastener is called solution B, and each is pumped by a separate infusion pump. Next, the grout injection material in which the A and B liquids are combined and mixed in the vicinity of the injection port is injected into a desired cavity or the like.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the present invention is not limited thereto.

Preparation of Super Absorbent Polymer Resin

A monomer mixture obtained by mixing sodium acrylate monomer (CH ₂ = CHCOONa) and acrylamide monomer (CH ₂ = CHCONH ₂ ) in a molar ratio of 1: 1 was dissolved in pure water to prepare a 20 wt% aqueous solution. 2.0 weight% of N, N'-methylenebisacrylamide was added to and dissolved as a crosslinking agent. To 100 parts by weight of the aqueous solution thus prepared, 1.0 parts by weight of triethanolamine was first added at room temperature, followed immediately by 1.3 parts by weight of sodium persulfate to initiate the polymerization reaction. The reaction started and exotherm began to occur. After 30 minutes, the reaction was completed and the exotherm was stopped and solidified. This was left to stand for 3 hours, after which an excess of 50% methanol aqueous solution was added to the solid gel, which was then pulverized with a high-speed grinding mixer and passed through a filter cloth to remove excess water and other soluble impurities. The cake gel thus obtained was dried in a vacuum dryer at 80 ° C. for 24 hours to completely remove moisture, and then ground in a ball mill filled with nitrogen gas to prepare a superabsorbent polymer compound in the form of a powdery resin.

Preparation of Silica Colloidal Solutions

3Kg (dry weight) of the superabsorbent polymer resin prepared above was added to 100 liters of alkaline silica sol having a silica concentration of 4% by weight, pH 10.3, and an average particle diameter of 12 nm, and then allowed to stand at room temperature (25 ° C.) for 30 minutes. The silica colloidal solution was prepared by separating the superabsorbent polymer resin using the filtration method and concentrating the silica sol.

[Preparation of grout injection material]

As shown in Table 1 below, the components of the grout injection material were prepared by dividing them into A liquid and B liquid, and then each of A liquid and B liquid was mixed to prepare a grout injection material having 1 m ³ .

Table 1. Formulation of Plasticized Grout Injection Material]

 division A amount B amount Silica Colloidal Solution Cement ¹⁾ Super Absorbent Polymer Resin CSA ²⁾ water Example 1 150 kg 300 kg 1 kg 10 kg 750L Example 2 150 kg 300 kg 0.5kg 10 kg 750L Comparative Example 1 150 kg 300 kg - 10 kg 750L Comparative Example 2 150 kg 300 kg 1 kg - 755 L

* 1) Cement: Portland Cement

* 2) CSA: DENKA CSA # 20 (non-condensing admixture containing calcium sulfoaluminate as a component) of Denka of Japan

Experimental Example 1: Measurement of Plasticity

In order to observe the change in viscosity with time after mixing the plasticized grout injection materials of Examples 1, 2 and Comparative Example 1, the viscosity by time using the vibrating viscometer (Japan AND Co., Ltd. Model SV-10) of FIG. Was measured continuously. The results are shown in FIGS. 2, 3 and 4, respectively. In addition, it is shown in Figure 5 to compare the time-phase viscosity graph of the conventional silicic acid-based plastic phase grout injection material. In Figures 2-5, the x-axis shows time, the left y-axis shows viscosity, and the right y-axis shows temperature, the lower curve in the graph curve shows the viscosity change over time of the blend, and the upper curve shows the temperature change of the blend. do.

As shown in FIG. 2, in the case of Example 1 having the highest amount of superabsorbent polymer resin, the plastic holding time was about 40 minutes, which is a level suitable for application in the art. In addition, as shown in FIG. 3, in the case of Example 2, in which the amount of the superabsorbent polymer resin added was half as compared with Example 1, the plasticity holding time was delayed slightly. However, in Comparative Example 1 in which the superabsorbent polymer resin was not added at all, as shown in FIG. 4, the plasticity retention time was excessively delayed.

In the case of Figures 2 and 3 it can be seen that the rising curve in the region of the viscosity 1,200 ~ 1,300cp descends and then rises again, which is a part of the vibration sensor part of the viscometer even though the gelation has already started in this region as a whole, the viscosity sharply increased In the case of measuring the viscosity of the suspended water discharged by the gel plastic destruction by vibration, it was confirmed through visual observation and touch. Therefore, it was confirmed that the point of virtually losing plasticity and changing to a non-plastic gel at the inflection point of the curved curve. In addition, it can be seen from the experimental results of Experimental Example 1 that the addition of an appropriate amount of the superabsorbent polymer resin is very advantageous for controlling the plasticity retention time.

On the other hand, the silicic acid-based plastic phase grout material of FIG. 5 has a higher plasticity viscosity than that of Comparative Example 1 of FIG. 4, but the retention time is delayed to a similar level. Sodium silicate-based plastic grout was found to be more likely to be lost if the groundwater was large.

Experimental Example 2 Measurement of Uniaxial Compressive Strength

For the plasticized grout injection materials of Example 1 and Comparative Example 2, the uniaxial compressive strength was measured over 1 day, 7 days and 28 days after mixing the respective components, and is shown in Table 2.

As shown in Table 2, the plasticized grout injection material of Example 1 was found to have a compressive strength level suitable for the purpose of backfilling or cofilling as a whole. As expected, the final strength tended to increase as the amount of cement added increased.

On the other hand, comparing Example 1, which includes CSA, and Comparative Example 2, which did not, it was confirmed that the initial strength of the formulation containing CSA in the early strength is relatively high. Therefore, in the plastic phase grout injection material of this invention, it was confirmed that it is preferable to use a suitable amount of a CSA agent in order to express roughness.

Table 2: Uniaxial Compressive Strength

division Uniaxial Compressive Strength (kg / cm ² ) 1 day 7 days 28 days Example 1 6.2 10.3 18.6 Comparative Example 2 4.5 8.5 16.9

Experimental Example 3: Durability Experiment

While comparing each of Comparative Example 1, which is the plasticized grout injection material of Example 1 and the conventional silicic acid-based plastic phase grout injection material, which has become a gel state, the uniaxial compressive strength before and after standing is measured for 180 days, and the appearance of specimens is compared. It observed and the result is shown in Table 3 and FIG.

[Table 3: Different uniaxial compressive strength before and after immersion for 180 days]

division Uniaxial Compressive Strength (kg / cm ² ) Before leaving After neglect Example 1 18.6 18.7 Comparative Example 1 19.4 18.1

As shown in Table 3, the gel of the plasticized grout injection material of Example 1 did not exhibit strength deterioration at 180 days of soaking, whereas the conventional silicate-based plasticized grout gel showed about 6-7% strength deterioration. It was confirmed that it occurred. This fact could be easily confirmed through visual observation as shown in FIG. 3.

The present invention provides a plastic phase grout injection material that can smoothly control the plasticity retention time, induce the rigidity of the plastic phase grout, and is advantageous in durability and long-term stability as a filler for filling the back voids or cavities.

Claims (4)

Grout juipjae 1m colloidal silica 100 ~ 200kg, cement 200 ~ 400kg, super-absorbent polymer as polyester resin, the absorption capacity greater than 250 times the self-weight (acrylate-amide) ³ per crosslinked copolymer 0.5 ~ 2.0kg and a calcium sulfo aluminate-based A plastic phase grout injection material comprising 5 to 20 kg of a fastener and water as the remaining components. The method of claim 1, A plastic phase grout injection material, characterized in that the average particle diameter of the silica colloid is 10nm or more. delete delete

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